The invention generally relates to flow control devices and more specifically to a check valve that allows a fluid to flow in a forward direction and prevents the fluid from flowing in a reverse direction.
A check valve is a one way flow device. When in an open position, a fluid passes through the check valve in a forward direction and when in a closed position the fluid is prevented from passing back therethrough in a reverse direction. Check valves are used in numerous fluid systems. One particular fluid system is a cooling loop of a heat exchanger in the cooling line of a nuclear power plant.
Check valves are generally mechanical devices that are self actuated from an open position to a closed position, by the flow of the fluid itself. When the fluid is flowing in the forward direction, the force of the fluid acts upon one or more components of the check valve such that the components are held in an open position permitting the fluid to pass through the check valve. When the fluid flow is in the reverse direction, the fluid acts on these components to close the check valve.
The fluid flowing within the cooling loop of a nuclear power plant is generally water diverted from a river or lake. Consequently, the water contains contaminates in the form of suspended solid particles. The water also has a high flow rate to meet the cooling demands of the nuclear power plant. The water and suspended particles combine to abrade both the valve components that are held in an open position by the water passing through the check valve as well as other surfaces of the check valve, such as those that define the passage, or passages.
The abrasion results in wear and tear on the valve that eventually causes the check valve to fail, permitting a reverse flow of at least some fluid through the check valve. When a reverse flow of any magnitude occurs, maintenance must be performed on the check valve. Maintenance generally involves the replacement of the check valve, which can be expensive both in labor and parts.
Based on the foregoing, it is an object of this invention to provide a check valve that is less susceptible to wear and tear so that the check valve requires less maintenance and/or less frequent maintenance.
It is a further object of this invention to provide a check valve that has components that are easily replaceable, such that the whole check valve does not have to be replaced due to the failure of a component part.
The invention is directed in one aspect to a check valve having a faceplate that defines a faceplate opening and the faceplate has an opening perimeter. The use of the relative terms reverse or forward, herein, are based on the forward flow of a fluid through the check valve. At least one rib is positioned within the faceplate opening dividing the faceplate opening into at least two opening sections. Each section has a continuous section perimeter with a portion thereof being coincident with a portion of a faceplate-opening perimeter.
This check valve also has an insert assembly having a base and a plurality of doors. The base has a forward surface and a reverse surface and defines a base opening. The base opening has a base perimeter. The forward surface of the base contacts the reverse surface of the faceplate. The insert has one door for each opening section of the faceplate. Each door has a forward face and is hingeably coupled to the base adjacent the base perimeter. The forward face of each door is contoured to engage the reverse surface of the faceplate and the reverse face of the rib that defines the opening section to be closed by the door. Seals are provided on the reverse faces of the faceplate and ribs at least in the areas acted upon by the doors.
As indicated above, each door is hingeably coupled to the base adjacent the base perimeter. This placement permits the doors to swing outwardly, away from the fluid flowing in the forward direction through the check valve. The hinges can also be positioned behind the faceplate. More specifically, the faceplate opening has a cross-section that is smaller than the base opening. Consequently, there is a lip formed by a portion of the reverse face of the faceplate. The hinges are placed behind the lip such that fluid can flow through the faceplate opening and the base opening without directly impacting the hinges. The hinges are thus protected from direct contact with the fluid and any solids suspended therein leading to a reduction in wear and tear on the hinges.
The faceplate and the base of the insert each have a cross-section with the cross-section of the faceplate being greater than the cross-section of the base creating a stepwise cross-section of the check valve in the forward direction. The stepwise cross-section defines a seat in the reverse surface of the faceplate. The base fits into a complementary shaped valve body and rests on a seat therein. The base is secured in the valve body by the faceplate, which is temporarily attached to the valve body. This permits easy replacement of the faceplate, insert, or both with reuse of the valve body.